The objectives of the proposed research are to determine the annual cycle of vibrios and related organisms in the water, sediment and aquatic flora and fauna of a tank and canal of a cholera endemic area, to identify those species of Vibrio, including Vibrio cholerae 01 and non-01 and Vibrio parahaemolyticus, found in these areas, to examine freshly isolated Vibrio strains for presence of extrachromosomal elements and to develop a genetic system for these organisms. Thus, studies on the seasonal abundance and distribution of Vibrio and related species from a water supply in a cholera endemic area (Bangladesh) will be continued. The ecological studies will include examination of water, sediment, flora and plankton samples collected at appropriate intervals of time for determining the seasonal abundance and distribution of Vibrio spp. Isolated strains will be subjected to extensive numerical analysis, examined for enteropathogenicity and antibiotic resistance patterns, and analyzed for presence of extrachromosomal genetic elements. The relationship of non-01 strains of V. cholera isolated from the water supply and from the Chesapeake Bay to classical and El Tor V. cholerae will be studied by systematic analysis and DNA/DNA hybridization studies. Analysis of cytotoxic and enterotoxic factors on non-01 vibrios, of V. parahaemolyticus and of Aeromonas hydrophila will be pursued on both an ecological and molecular genetic basis. Correlations will be sought between indivdual strain characteristics and presence of extrachromosomal elements, and factors relating to pathogenicity and natural distribution. By using a computer based system, development of an on-line identification system for Vibrio species will be developed.